[Recovery from depression. Psychobiologic criteria of recovery].

Many biological studies of mood disorders attempted to identify markers linked with neurobiological effects of antidepressant treatments. One has to acknowledge that presently there are no useful markers of depression, as for instance markers of cancer. However, abnormalities have been noted in clinically heterogeneous subgroups of patients. Compared to the great number of investigations dealing with biological criteria in the diagnosis of depression, only a few studies addressed the issue of the course of biological parameters prior to, during and after treatments. But if these abnormalities are closely related to the depressive condition, it is important to establish whether they disappear when patients recover. Only longitudinal studies can answer these questions. Moreover, the few available studies concern the therapeutic response, rarely recovery. To declare that a patient recovered from depression means he recovered from the depressive episode, not from the illness itself. The sometimes discordant results reported by different groups on the course of biological parameters measured during depression may be partly due to differences in the exact time when one decides a patient recovered: early recovery when investigations take place between 3 weeks and 4 months after the beginning of the episode--a period of frequent relapse--and when persisting biological abnormalities will unmask the vulnerability of apparent clinical recovery. In some studies, only the investigations performed after 4 months of evolution demonstrated a normalization of initially disturbed biological indices, concomitantly with a genuine recovery, protecting against relapse. Thus, the biological normalization may be prognostically interesting, revealing that a period of remission has consolidated or not. Moreover, some biological abnormalities are said to be constitutional.(ABSTRACT TRUNCATED AT 250 WORDS)